This is a continuing study of the influence of opioids on the biosyntheses in brain of specific proteins. We have already found that the phosphorylation of some synaptic membrane proteins is influenced by opioid treatment in rats. Chronic morphine administration decreased the rates of phosphorylation of many membrane proteins, while the acute administration of many opioids including morphine, methadone, met-enkephalin and beta-endorphin, produced biphasic effects; a large increase in phosphorylation followed by a reduction to almost zero. Since neurotransmitter release is inhibited by opiates, we intend to measure simultaneously the stimulated release of dopamine from striatal synaptosomes and the phosphorylation of specific synaptic proteins, and examine opioid effects on these processes. We are also examining endorphin turnover in rat brain as affected by opiate administration.